Sweetening and stabilizing hydrocarbon oils



Patented Dec. 9, 1952 SWEETENING AND STABILIZING HYDROCARBON ons Johan C. D. Costerhout and Thomas C. Roddy, Jr., Port Arthur, Tex; assignors to The Texas a Company, New York, N. Y., a corporation of Delaware Application September 22,1951, Serial No. 247,844

. G'Cla-ims. (Cl. 19%30) This invention relates to the treatment of hydrocarbon oils, particularly light hydrocarbon oils adapted for motor fuel, and contemplates I treating the hydrocarbon oil with an organic metallic salt in combination with certain oxidation inhibitors and metal deactivators to effect sweetening and stabilizing of the oil.

In accordance with the invention light hydrocarbon oil, such as gasoline or naphtha containing mercaptans, is simultaneously contacted with a combination of reagents which includes an organic metallic salt, a phenylene diamine, and a nitrogen-substituted salicylalamino alkane. The organic salts adapted for the practice of the invention includesalts of copper, cobalt, lead or zinc, particularly oleates and naphthanates. The phenylene diamine used is preferably a paraphenylene diamine or a dialkyl derivative thereof, such as N,N'dialkyl-para-phenylene diamine. iThe salicylalamino alkane used is preferably a polysalicylamino polyalkane, such as N,N'di- 'salicylal-l-Z diaminopropane. By treatingthe hydrocarbon oil with the combination of the three reagents, the organic metallic salt, the paraphenylene diamine or dialkyl derivative thereof, and the N-salicylalamino alkane, a conversion of the mercaptans to produce a sweet product is accomplished while simultaneously a stabiliza- Ition against oxidation is efi'ected.

The invention is adapted particularly for the treatment of hydrocarbon oil which although sour and yielding a positive reaction in the doctor test contains. a relatively small mercaptan con:- tent. Thus, the invention is especially adapted to thetreatment of such stocks as light naphthas ing system and sent to tankage and the process of the-invention may be applied by simply introducing the three additives into the transfer line. The materials introduced are soluble in the light 1 hydrocarbon and the-mixing in the pipe and in the tank where the distillate is received is'a'dequate to effect the desired dispersion of the treating materials in the oil. 7

' Asshowing the effect of the treatment with the'materials contemplated in the invention some comparative tests were made in treating a cracked gasoline which had previously received treatment with a metallic alkali hydroxide in a solutize'r unit. This gasoline had a mercaptan sulfur'c'o'nv tent of 0.0015% and showeda positive doctor test both initially and after standing for a'period of some 12 hours. It showed a copper dish'gum test of '39 mgs./100 cc. and in the .ASTM oxidation test had an induction period of 165 minutes.

from fiuid catalytic cracking operations-and'low mercaptan straight run naphthas which can be rendered completely sweet and stable against oxidation without other treatment or addition of inhibitors. The process is also adapted as a finishing. treatment to sweeten and stabilize stocks which have previously received treatment for the removal of mercaptans such as alkaline treatments. Thus, for example, the well-known solutizer process in which the hydrocarbon is treated with alkali. metal hydroxide in the presence of varioussolutizers does not produce a sweet prodjuct and the hereindescribed process is well adapted for treating such product to render it ,lsweetas well as stable against oxidation.

- The process possesses a particular advantage 'in that it does not require the usual agitators or reaction vessels commonly employed in treating'processes. Thus, the distillate can beta'ken directly-fromthe stills'or from a preceding tr'eat- The gasoline was separated into four different portions and each portion was given a different treatment. N,N'disecbutyl paraphenylene diamine was added to the first portion in a quantity equivalent to 10 lbs/1000 bbls. of gasoline.

The same quantity of the para-phenylenediamine and copper naphthenate in an amount equivalent to 5 lbs/i000 bbls. was added to the second portion. The same quantity of the para-phenylenediamine and N,N' disalicylal-l-2 diamino propane equivalent to 5 lbs./ 1000 bbls. was added to the third portion. All three additives were vadded to the fourth portion each in the same quantity as used in treating the other portions."

(The N,N'-clisalicylal-l-z-diamino propane used was in its commercial form consisting ofa solution in xylene, one part xylene to 4 parts active ingredient.) The following table gives the-results obtained in the comparative treatments:

It will be seen that the gasoline treated with the paraphenylenediamine only was still. .not sweet but ithad a good induction period. 'The 'than 0.75:1.

treatment with the paraphenylenediamine and copper naphthenate produced a product which was sweet after standing but the induction period was very low. The treatment with the paraphenylenediamine and the N-salicylalamino alkane did not sweeten the gasoline but yielded a product having a good induction period. The treatment with the combination of the three materials yielded a product which was sweet after ing was only very slightly positive to the doctor test and after standing overnight was completely negative. The combination of the cobalt naphthenate and the salicylalamino-alkane in the same quantities was found equally effective in treating a kerosene stock yielding upon overnight standing a product negative to the doctor test.

The organic salt dosage varies somewhat with the mercaptan content of the stock to be treated and also with the type of stock treated. Thus, for example, straight run stocks are somewhat more difficult to sweeten than cracked stocks containing olefins. In any case the quantity employed is much less than the stoichiometric quantity on the basis of the mercaptan content. Thus, in many cases, the amount of organic salt employed approximated of the stoichiometric. In

In the further description of the invention,

treated with various proportions of N,N-disali- 1 cylal-l-2-diaminopropane and copper naphthenate. The various ratios of these treating materials are plotted as abscissa and the induction periods in minutes of the ASTM oxidation stability test are plotted as ordinates] based on tests using one pound of copper naphthenate per thousand barrels of gasoline treated,

curve B is based on fivepounds ofcopper naphthenate per thousand barrels and curve C is based on 10 pounds of copper naphthenate per thousand barrels. It will be seen the three curves rise rapidly to a point represented by a ratio of 0.7521. In plotting the data beyond this point it is best represented by a common curve D showing that increased ratios up to a ratio of 2:1 produced only a very slight increase in the induction period. It is shown, therefore, that the ratio of the salicylalamino alkane to copper naphthenate should be about 1:1 or atleastas high as 0.75:1.

.In Figure 2 the ratios of the N,N-disalicylal- .l-Z-diaminopropane to copper naphthenate are plotted as abscissa and the ASTM gum in grams/ 100. cc. is plotted as ordinates. The data with the three different quantities of copper. naphthenate. (i. e. 1 1b., lbs. and.l0.lbs per 1000 bbls.)

correspond so.closely that they are represented by the single curve in the graph. It is shown that the point of minimum gum is approximately at the ratio of 0.75:1 and that higher ratios of the metal deactivator do not lower gum formation.- Thus, from the standpoint of both induction period and gum it is shown that the ratio of the salicylalamino alkane to copper naphthenate should be about 1:1 or at least not lower Cobalt naphthenate is very effective in the process. By way of example, a cracked naphtha was treated by adding cobalt naphthenate in a quantity equivalent to lbs/1000 barrels of the naphtha, N;Ndisalicylal-1-2 diaminoproprane Curve A is :z

typical operations quantities approximating 5 pounds per thousand barrels have been found adequate and in fact, increasing the quantity to 10 pounds .per thousand barrels produced very little, if any, improvement. The sweetening reaction appears to be largely a catalytic reaction in which the paraphenylenediamine plays a part, that is, both the organic metallic salt and the paraphenylenediamine function in the sweetening reaction and the paraphenylenediamine sta bilizes the product in storage. The time available for sweetening is also to be considered in deciding on the strength of organic metallic salt to be employed. Thus the holdup of stocks in tankage will vary from plant to plant.

Temperature is not particularly critical in the process although increasing the temperature from about F. to about F. caused a marked improvement in the rate of sweetening. Increasing the temperature above 100 F., however, did not appear to produce any increase in the rate of sweetening.

Air or oxygen blowing is not necessary for carrying out the process and, in fact, the process can be conducted satisfactorily in closed systems in which practically no air is present. However, air blowing has a tendency to increase somewhat the rate of sweetening.

v The presence of traces of alkali metal hydroxide accelerates the rate of sweetening. Thus. for example, in treating a naphtha, having a mercaptan sulfur content of 0.019 gram per liter, with copper naphthenate, 10 lbs/1000 bbls. of naphtha, N, N' disalicylal-l-2-diaminopropane, 7.5 lbs/1000 bbls., and N,N disecbutyl paraphenylenediamine, 5 lbs/1000 bbls., the mercaptan sulfur'content in one days standing was rcduced to 0.008 gin/1., while with sodium hydroxide'addedin a quantity amounting to one milligram of 15 Baum NaOH per quart, the mercaptan sulfur content in the same time of standing was reduced to 0.004. Thus, it is advantageous whenemploying the herein described process'to completely sweeten and stabilize an oil previously subjected to a treatment with caustic, to avoid a complete removal of the caustic from the preceeding treat and permit traces of caustic to remain in the oil which is passed to the final sweetening and stabilizing treatment.

Although a preferred embodiment of the invention has been described herein, it will be understood that various changes and modifications may be made therein, while securing to a great.- er or less extent some or all of the benefits of the invention, without departing from the spirit and scope thereof. 4 r We claim:

1 The method of treating hydrocarbon oils containing mercaptan sulfur to effect simultaneous sweetening thereof and stabilization against oxidation that comprises contacting the oil with an organic metal salt, a paraphenylenediamine and an N-salicylalamino alkane to subject the oil to the combined action of said contacting materials.

2. The method of treating hydrocarbon oils containing mercaptan sulfur to effect simultaneous sweetening thereof and stabilization against oxidation that comprises contacting the oil with an organic copper salt, an N,N dialkylparaphenylenediamine and a polysalicylalamino polyalkane to subject the oil to the combined action of said contacting materials.

3. The method of treating hydrocarbon oils containing mercaptan sulfur to effect simultaneous sweetening thereof and stabilization against oxidation that comprises contacting the oil with copper naphthenate, an N,N' phenylenediamine and a polysalicylalamino polyalkane to subject the oil to the combined action of said contacting materials.

4. The method of treating hydrocarbon oils containing mercaptan sulfur to effect simultaneous sweetening thereof and stabilization dialkyl-para- 'Lil 6 against oxidation that comprises contacting the oil with copper naphthenate, I T,N disecbutylpara-phenylenediamine and N,N' disalicylal-l- Z-diaminopropane to subject the oil to the combined action of said contacting materials.

5. The method of treating hydrocarbon oils containing mercaptan sulfur to effect simultaneous sweetening thereof and stabilization against oxidation that comprises contacting the oil with cobalt naphthenate, an N,N' dialkylparaphenylenediamine and a polysalicylalamino polyalkane to subject the oil. to the combined action of said contacting materials.

6. The method of treating hydrocarbon oils containing mercaptan sulfur to effect simultaneous sweetening thereof and stabilization against oxidation that comprises contacting the oil with cobalt naphthenate, N,N' disecbutylpara-phenylenediamine and N,N' disalicylall-z-diaminopropane to subject the oil to the combined action of said contacting materials.

JOHAN C. D. OOSTERHOUT. THOMAS C. RODDY, JR.

No references cited. 

1. THE METHOD OF TREATING HYDROCARBON OILS CONTAINING MERCAPTAN SULFUR TO EFFECT SIMULTANEOUS SWEETENING THEREOF AND STABILIZATION AGAINST OXIDATION THAT COMPRISES CONTACTING THE OIL WITH AN ORGANIC METAL SALT, A PARAPHENYLENEDIAMINE AND AN N-SALICYLALAMINO ALKANE TO SUBJECT THE OIL TO THE COMBINED ACTION OF SAID CONTACTING MATERIAL. 